Last summer groups of farmers representing four different CSF Priority Catchments in the county were challenged, by CSF officers, to reduce soil erosion on a sloping sandy loam field while producing the highest gross margin crop of wheat.
Even before this season’s delayed harvest their choices have thrown up some interesting results, according to challenge co-ordinator Simon Draper.
“By assessing the soil structure, the teams had to decide what would be the most suitable cultivations for establishing winter wheat to maximise yield and minimise the effects on the environment,” says Mr Draper.
The field chosen at Easton College was after maize and posed a definite but not especially high risk given the soil type and gentle slope, he explains. “You would have to do things wrong to cause erosion – and some of the groups clearly did.”
Students studied the 2ha (5-acre) plots where the teams not only had to deal with getting higher yields, but also how to deal with the maize stubble.
“They were also free to choose varieties to see if any preferred different cultivation techniques,” says Mr Draper.
The students assessed the plots during the season to see how the teams’ different approaches affected soil structure and subsequent water run-off and erosion, and to check whether the crops were still on course to achieve the targeted yields, he explains.
Their measurements, by scoring run off and soil erosion caught at the end of each plot, showed that reduced cultivations led to most run-off, while soil erosion was worst from the ploughed plots. There appeared to be no varietal affect.
“But it was interesting to see that the plot where the Hundred farmers chose to leave a rough seed-bed, using a plough and furrow press, and followed up with a Carrier spring tine drill, they got minimum run-off and erosion.”
Right up to July the plots appeared equally uniform, even and potentially high yielding, notes Mr Draper.
“However, at the beginning of July we assessed root development by measuring the volume at different depths in the soil and found some interesting variation in growth between the plots.
“The best root distribution followed the Carrier drilling which may be because the machinery used was lighter.”
After a fortnight of dry weather in mid-July some drought stress in the plants was starting to show. “So we took some leaf-rolling scores by assessing how tightly the flag leaves were curled around mid-day.
“Again this indicated, not unsurprisingly, that where root distribution was best there was less leaf rolling.
“The distribution in the Nar group’s disced plot was particularly uneven with roots concentrated towards the top of the soil profile. But given the amount of rain we’ve had since then, it will be interesting to see how it has performed. If the rain fell before the crop senesced it may even have benefited.
“We hope to repeat the challenge next season, with and without leaving the straw on the soil surface, and with and without discing it in.”